Income Taxes (Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Net operating loss carryforwards:
Net operating loss carryforwards:	$ 42	$ 47
Tax credit carryforwards:	176	181
Federal
Net operating loss carryforwards:
Net operating loss carryforwards:		11
Tax credit carryforwards:	174	176
State
Net operating loss carryforwards:
Net operating loss carryforwards:	42	36
Tax credit carryforwards:	2	5
Ameren Missouri
Net operating loss carryforwards:
Net operating loss carryforwards:	0	4
Tax credit carryforwards:	124	118
Ameren Missouri | Federal
Net operating loss carryforwards:
Net operating loss carryforwards:		3
Tax credit carryforwards:	124	118
Ameren Missouri | State
Net operating loss carryforwards:
Net operating loss carryforwards:	0	1
Tax credit carryforwards:	0	0
Ameren Illinois
Net operating loss carryforwards:
Net operating loss carryforwards:	26	30
Tax credit carryforwards:	7	4
Ameren Illinois | Federal
Net operating loss carryforwards:
Net operating loss carryforwards:		4
Tax credit carryforwards:	5	3
Ameren Illinois | State
Net operating loss carryforwards:
Net operating loss carryforwards:	26	26
Tax credit carryforwards:	2	1
Other
Net operating loss carryforwards:
Net operating loss carryforwards:	16	13
Tax credit carryforwards:	45	59
Other | Federal
Net operating loss carryforwards:
Net operating loss carryforwards:		4
Tax credit carryforwards:	45	55
Other | State
Net operating loss carryforwards:
Net operating loss carryforwards:	16	9
Tax credit carryforwards:	$ 0	$ 4